1. Field of the Invention
This invention relates in general to a shield for protecting electronic instruments sensitive to electromagnetic energy and more particularly to an ablating shield for attachment to a missile.
2. Background of the Invention
Missiles, particularly ship-launched missiles, are exposed to high levels of electromagnetic radiation while on the launcher and in the proximity of the ship during launch. The radiation levels are particularly high if spotlighted by the main beam of radar. Electronic components in missiles have been found to be adversely affected by high levels of electromagnetic radiation which can cause serious performance degradation by digital upset, bias shut-off or possibly burn up. The energy is coupled by the missile body and by internal circuitry via apertures on the surface of the body. The apertures may be nonfunctional openings in the body surface that expose internal wiring to direct radiation as well as allowing the skin current induced on the outer surfaces to flow inside, or the apertures may be intentional, namely antennas.
Conventionally, circuit components associated with antenna output have been protected by series attenuators that are automatically switched out when the distance from the radiation source causes the radiation received to drop to acceptable levels. Such attenuators are very costly.
Therefore, it is desirable to have a shield for protecting electronic components of a missile while in the proximity of ship and for ablating shortly after launch to allow proper functioning of the electronics.
It is further desirable that such a shield requires no internal modification to the missile. It is further desirable that such a shield is easily attachable to a missile.
It is further desirable that such a shield be relatively insensitive to electrostatic discharges such as generated by personnel and to physical shocks of handling and storage.